Why Extend Jason Bay Now?

I was one of the very few people unhappy (extremely so) with Jason Bay's acquisition at 3:59:59 on July 31, so that will obviously color the reaction to this piece, but try to hear me out. Why are the Boston Red Sox so desperate to extend Bay at this exact point in time? As I see it, here are the potential results from this point forward...

1. Jason Bay continues exactly as he has been, putting up a .290/.370/.525 or so line. 2. Jason Bay hits a wall and produces a .250/.330/.440 line. 3. Jason Bay has a career year (or career half-year), with a .330/.400/.580 line.

Now, if No. 1 happens, then there is nothing gained by signing him now versus the future because he's done exactly what the Red Sox expect him to do. Signing him now only removes the team's ability to see if he can maintain that .900 OPS for the latter half of 2008 in the superior league.

If No. 2 happens, then Boston isn't locked down with a mediocre talent's ridiculous contract, having already done that at a number of positions. If the Red Sox think 2009 was an outlier, they can sign him to a severely undervalued contract, saving millions over a March 2009 signing.

No. 3 is the only situation where Boston would be endangered because his value would increase greatly with a contract-year push. However, chances are the Red Sox wouldn't bend over backwards to sign a 30-something outfielder to an $18 million per year contract. However, some other teams, perhaps in the Bronx, would do so happily.

I can understand the counter argument that the Sox are unlikely to negotiate during the season, and they like to remove potential risk from the system, but signing people before the team can truly determine what they'll produce has led to an execrable, overpriced left side of the infield and millions wasted each season.